Automatic test equipment for testing the performance of RF communications systems, radar systems and other RF-related distribution components has been available for a number of years and is well established. A mix of scalar and vector network analyzers can be used to obtain a variety of S-parameter S11, S12, S21, S22 measurements in addition to phase and delay measurements on RF components.
Performing a swept frequency response on an RF distribution chain is of paramount importance when testing an ESM system. Specifically, a manufacturer or end user will specify the minimum and/or maximum insertion loss S21 allowed for a particular path to insure proper system performance.
An ESM system encompasses different types of systems. One type of system is electronic support measures which is geared towards supporting EW (Electronic Warfare). It is essentially scanning the radio spectrum but the surveillance is in a different context.
A typical ESM system is usually subjected to periodic calibration involving weeks of rigorous testing in order to guarantee continued system compliance with manufacturer's and/or end user's parameters. Manual testing of an ESM system has proven to be a long and cumbersome effort and prone to operator error. Automation of the testing process reduces the effort involved as well as reduces the potential for operator error. Conventional test equipment is typically used to conduct these measurements. Once an ESM system has been subjected to, and successfully passed a thorough battery of tests, it is ready for deployment. Herein lies the weakness of the current test equipment and test systems approach.
Once deployed, the typical ESM system is subjected to harsh physical and environmental elements. Even with the best of care, components within the ESM system are subject to degradation and/or failure, for example, when exposed to extreme operating conditions. The absence of some form of built-in-testing (BIT) or periodic performance monitoring system often results in an ESM system whose performance parameters can be considered questionable at any given point after deployment. As a result, the need for some form of embedded automatic test system becomes a necessity in order to maintain accurate and repeatable performance of the ESM system. In this connection, embedding the automatic test system with the ESM system may be considered to be situating the automatic test system such that it is readily available for testing the ESM system at its operating site without requiring the ESM system to be moved, for example, to a special testing facility.